ElectroElectro surg surgiicalcal unitunit

PURPOSE •ESU are used for surgical cutting and for controlling bleeding by causing coagulation “hemostasis” at the surgical site.

•It is “high frequency diathermy” involves the transference of electrical energy into heat which ,when impact to the bodily tissues, will heat the normal cell fluid, eventually through it is boiling point.

•What dose “DIATHERMY” mean? DIA = through

THERMO = temperature heat

Principle• ESU machine is an alternating current source that

operates at radio frequency “RF”.• A high frequency current flowing through active electrode

“high current concentration”.• Cell ruptured-fumes or evaporates.• Return path through dispersive electrode “low current and

heat dissipates”.• Patient is included in circuit.• Current concentration or density depends on the size of

the area through which the current flows.• HF generation can be activated by a foot switch or finger

switch on the surgical handle.

System Components

Electrosurgery Unit

Active Electrode Dispersive Electrode

RFGenerator

Active

electrode

Body

Patient

electrode

\..ESU Principle.ppt

Effect of RF on cell

• When a high frequency current applied to the tissues the tissues gets turn apart and get the following effect:

1. Thermal effect.

2. Electrolytic effect.

3. Faradic effect.

Operating frequency and typical value

• Operating frequency of solid state surgical diathermy machine is 300 KHz –to-3MHz

• Monopolar :CUT “0-to-350”watts for load 5 COAG”0-to-100” watts

• Bipolar : CUT “0-to-50” watts

COAG “0-to-10” watts

Types of ESU

Spark gap generator – 1924

• Still in use today “urology , open- heart surgery”.

• Spark gap / vacuum-tube device use spark –gap circuits to generate high frequency waveforms.

• It is not offer the same safety feature as solid state unites.

Recent technology• Argon/argon enhanced technology.• It uses a computer-controlled tissue feedback

system that senses tissue impedance and automatically adjusts the current and output voltage to maintain a constant surgical effect .

• It is reduces the need to adjust power setting for different types of tissue.

• It is also gives improved performance at low power setting to reduce the risk of patient injury.

Solid state device - 1968• It is more recent and more prevalently used

technology.

• Contain oscillator circuits and transistor-based amplifier that vary the frequency and modify the shape of the line signal to create an array of different waveforms for pure CUT,COAG, BLEEND .

• Highly safety.

OK!, but how can I OK!, but how can I control so accurately the control so accurately the

temperatures in the temperatures in the tissues ?tissues ?

Modes of Electro surgery

Monopolar surgery

Bipolar surgery

Modes of electrosurgery

• Electrotomy/cutting

• desiccation / coagulation

• Blend

• fulgurations

General Block Diagram

MainCPU

Logic/Control BoardRelyboard

Audio tonegenerator

LED display

Front panel

Power O/P or RF board

Isolationtransformer

Powersupply

Footswitch

Patient returnelectrode

RF output